on my PicoScope 3403D (usb3.0) the waveform update rate is only about 13 waveforms/s in scope mode. Because I want to view an audiosignal with analog feeling, I need at least 30 updates/s. Is there any way to increase it, on what it depends, is it a willful limit?

Can you repeat the test for me, but this time use Views->Channels and disable the display of all channels. Run the test and then check the update rate. This will prevent the software from requesting downsampled data from the device to display on the screen after each waveform has been collected before starting the next. Once the collection is complete you can re enable the display of the data.

I have been getting 40+ wf/s at 1GS/s, although the speeds do vary a bit depending upon what other applications on the PC are doing, and also the specification of the PC being used.

Can you repeat the test for me, but this time use Views->Channels and disable the display of all channels. Run the test and then check the update rate. This will prevent the software from requesting down sampled data from the device to display on the screen after each waveform has been collected before starting the next. Once the collection is complete you can re enable the display of the data.

I have been getting 40+ wf/s at 1GS/s, although the speeds do vary a bit depending upon what other applications on the PC are doing, and also the specification of the PC being used.

Because you system has quad cores the value you see needs to be multiplied by 4.
So 1 core (the core picoscope is running on) is utilized by 96%, so you are at the max of your PC.
Some processes can be split on multiple cores / threads. others are not.
But your assumption of 24% is wrong !

@Benno
Why my assumption is wrong? The max of my PC would be 4 x 100%.

Can it be true that PicoScope doesn't really supports multicore? But the manual says "...will greatly benefit from a multi-core processor". At the moment it doesn't! One core is at the end and the others are bored.

@Martyn
What CPU do You working on to get > 40 wf / s? USB3.0 doesn't speed up the waveform update rate in scope mode (short timebase)? Isn't it?

...that only single core performance speed up PicoScope and I think you know. Until Picotech doesn't really wangle multicore and usb3 it would not be a tool i can work with. The note in the manual "will greatly benefit from a multi-core processor" isn't the truth. Sorry, but I think You should fair play...

There are many things that can affect performance, your test showed a difference between different USB 3 cards and how they operate in USB2 mode.

Was this just using a USB2 cable, and how did the USB2 mode on the onboard AMD port perform quicker than native USB3.

Performance of the O/S, and any other services that are running will also have an impact. I made sure that I turned off or disabled anything that was unnecessary, and made sure that my system was fully updated, and with the latest hardware drivers installed.

I will refer your comments about the multi core to the development and documentation teams, and reply back when I have an answer.